1. Field of the Invention
The invention relates to a fastening system for a plate-shaped structural element on a pitched roof, wherein the plate-shaped structural element is bordered in a water-tight manner in a frame of profiled beams, to form a module, and fully replaces the roof covering, wherein the eaves-side and ridge-side cross beams of the frame which run transversely to the ridge-eaves direction have profiles which are matched to each other and engage in each other in order to install modules which are adjacent in the ridge-eaves direction, these profiles forming a rain-proof joint such that the modules partially overlap in the longitudinal direction only in the region of these cross beams. Plate-shaped structural elements to be considered are, in particular, rectangular photovoltaic modules (PV modules) or solar thermal modules.
2. Description of Related Art
A fastening system of this type is known from DE 203 03 431.7-U1. In this fastening system for a plate-shaped structural element on a pitched roof, in particular for a photovoltaic module, the plate-shaped structural element replaces the roof covering and rests on at least two beams arranged in the ridge-eaves direction, wherein beams are provided at all edges of the plate-shaped structural element and form a base frame that supports the plate-shaped structural part, engages laterally around it and borders it on the top side in a water-tight manner.
In the text which follows, the ridge-eaves line is denoted as the longitudinal direction, and a parallel to the ridge or to the eaves is denoted as the transverse direction. In the fastening system mentioned above, the plate-shaped structural elements are laid so as to overlap in an imbricated manner in the longitudinal direction. A photovoltaic module has a laminate with photovoltaic elements and a frame. Even during production, a plurality of photovoltaic elements of a laminate are electrically connected in series to form a voltage chain in order to make a higher voltage available. A disadvantage in this connection is that an element which is in shade reduces the efficiency of the entire chain. Laminates are therefore designed in such a way that no shading takes place after they have been properly installed on the roof. At present, the majority of laminates are produced so as to form modules for on-roof installation, the modules being installed on is beams in the manner of a roof hook over the roof covering. A plurality of modules lie parallel next to each other in the longitudinal direction and in the transverse direction so that no shading takes place. The beams on the edges cover the top side of the laminates only in an extremely narrow edge region, and therefore virtually the entire surface of a laminate is covered by photovoltaic elements.
In the case of in-roof laying which has been conventional to date and where photovoltaic modules replace the roof covering, the imbricated overlapping in the longitudinal direction means that the overlapped part of the laminate may not contain any photovoltaic elements. This makes production more expensive and requires special production procedures.